Using lambda in .where()

[ste-goldstein]

I came across this:

ndvi_stack = ndvi_stack.where(lambda ndvi_stack: ndvi_stack < 0.92, 0.92)
ndvi_stack = ndvi_stack.where(lambda ndvi_stack: ndvi_stack > -0.08)

Is this the same as:

ndvi_stack = ndvi_stack.where(ndvi_stack < 0.92, 0.92)
ndvi_stack = ndvi_stack.where(ndvi_stack > -0.08)

and if yes, why should I use one over the other ?

[keewis]

passing a callable is roughly equivalent to

f = lambda x: x < 0.92
ndvi_stack.where(f(ndvi_stack), 0.92)

This allows code like this to work:

ndvi_stack.where(lambda x: x <0.92, 0.92).where(lambda x: x > -0.08)

In the example you gave there's not really a good reason to use a callable since you're not chaining method calls or renaming variables.

[ste-goldstein]

Tks. So in your second example, using lambda allows applying the second .where() to the result of the first one ?

[keewis]

yes, exactly